Synthesis and Miscibility of Comb Poly[11-(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl acrylate]s Prepared by ATRP

Abstract

Comb poly[11-(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl acrylate]s were synthesized by atom transfer radical polymerization (ATRP) of 11-[(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl] acrylate from a multifunctional macroinitiator. The macroinitiator was prepared by first copolymerizing 2-[(2‘-tetrahydropyranyl)oxy]ethyl acrylate (r1 = 0.88) with 11-[(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl] acrylate (r2 = 1.11) under ATRP conditions, followed by hydrolysis of the randomly distributed tetrahydropyranyl groups and conversion of the resulting hydroxyethyl acrylate groups to 2-(2‘-bromopropanoate)ethyl acrylate initiating sites. The comb polymers contained 45−128 repeat units according to GPC measurements relative to linear polystyrene or 52−237 repeat units according to GPC−RI−viscometry−right angle laser light scattering measurements. The biphasic regions of the smectic A to isotropic transition of the comb polymers with pdi = 1.27−1.87 are extremely narrow, with full widths at half of the maximum peak intensity (fwhm) = 2.38−8.28 °C, in contrast to that of the corresponding polymer prepared by conventional radical polymerization (fwhm = 17 °C). The breadth of the biphasic region of binary blends of the comb polymers with poly[11-(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl acrylate]s of a variety of architectures (linear, three-arm star, comb) increases linearly with the difference in the end group (and therefore branching) density of the two components, regardless of the combination of molecular architectures.